1. Field of the Invention
This invention relates to an improved apparatus and method for providing a high-humidity environment for produce in a storage structure.
2. The Prior Art
It is a common procedure to place farm produce, such as potatoes, onions, carrots and the like, in storage until they can be shipped to the produce distribution system. However, it has been noted that produce such as potato tubers become rapidly dessicated unless stored under an atmosphere of high humidity and a moderately cool temperature. The harvested potato tuber also undergoes certain changes during storage including the conversion of starch to sugar and the oxidation of the sugar during respiration with the production of carbon dioxide. Potato mass is thus lost during storage at a rate dependent upon the rate of water loss and respiration.
Furthermore, the starch/sugar ratio may be unfavorably altered depending upon (1) the conversion rate of starch to sugar and (2) the oxidation of the sugar. Additionally, these changes in the potato undergone during storage generate heat which, unless removed, substantially accelerates the deterioration of the potato. It is, therefore, customary to store potatoes where they can be cooled. However, it has been found that when potato tubers are stored at temperatures within the range of about 0.degree. C (freezing) to about 7.degree. C to prevent tuber rot and decay, the respiration process is sufficiently retarded to allow an increase in the sugar concentration. Accordingly, potato tubers stored under these colder conditions for substantial periods of time develop a high sugar concentration rendering the potato tubers inedible.
As a result, it has become conventional practice to store the potato tuber in a high-humidity environment (95-100%) which is cooled to a temperature range of approximately 7.degree. C to 13.degree. C. However, this temperature range permits an increased tendency for the potato tubers to develop microbial storage diseases, such as blight, dry rot, etc. It has, therefore, become conventional to spray or dip the potato tubers in a chemical solution as one means for inhibiting these storage diseases.
These recent advances in the long-term storage of produce have, correspondingly, resulted in the development of additional difficulties, such as (1) water accumulation in the storage structure from condensation of the moisture of the high-humidity environment with (2) a resultant waste of water and (3) decreased equipment life. Particularly injurious to equipment is arcing and corrosion of the electric motors which are operated in the high-humidity environment. Electric motor arcing and corrosion damage occurs even though it has become a common practice to double dip and bake the motors during manufacture to specifically combat these problems.
Additionally, the maintenance of a high-humidity environment consumes vast quantities of water which becomes critical particularly in the arid regions of the West where potatoes are grown under irrigation. It would, therefore, be an improvement in the art to provide an apparatus and method for providing a cooled, high-humidity environment for a storage structure for produce wherein the apparatus (1) reduces water accumulation, (2) recirculates condensate from the air distribution system, (3) provides for an increased life expectancy for the equipment, particularly the electric motors involved in the apparatus, and (4) accommodates injection of chemicals to combat storage diseases into the water so that the chemicals can be carried through the air distribution system or applied directly to the produce.